Preparation And Characterization Of A Molecularly Imprinted Polymer By Grafting On Silica Bead For The Patulin Determination

Patulin (g-lactone a-b insaturated {4-hydroxy-4H-furol [3,2-c] pyran- 2(6H)-one}) is a secondary metabolite naturally produced by a variety of fungi like Aspergillus, Penicillium and Byssochlamys. It has a broad spectrum of toxicity also against plants, protozoa and animals. For human beings, patulin has caused nausea, vomiting and gastrointestinal disturbances. Patulin has been found mainly in apples and its products, and occasionally in other fruits. The concern of governments and researches, in general, has significantly risen in the last years due to the high occurrence of patulin. Analytical methods with higher accuracy, lower detection limits and higher specificity may be achieved by the combination of the Molecularly Imprinted Technology(MIT) and High Performance Liquid Chromatography(HPLC).In this study, we tried to find a template subsitute instead of patulin to get molecularly imprinted polymers(MIPs) of patulin was prepared using template substitutes. In view of marketing and other conditions, 2-hydroxynicotinic acid, 6-hydroxynicotinic acid and coumalic acids were initially taken as substitute candidates and 6-HNA was finally selected under the help of Hyperchem(version 7.5) soft analysis and Isothermal Titration Calorimetry experimental assay. A patulin-selective polymer was successfully synthesized by molecular imprinting technology(MIT), with 6-Hydroxynicotinic acid as template substitude, acrylamide as functional monomers,ethylene glycol dimethacrylate as crosslinker and 4,4'-Azobis (4-cyanopentanoic acid) grafted silica(ACPA-Silica) as azo-initiator.The MIP was detected and characterized by SEM, Infrared red and Element content. It showed that percent grafting was 26.73% for APTS-Silica, while 27.18% and 68.17% for ACPA-Silica.In addition, the MIP was evaluated by SPE-HPLC method and oscillation adsorption. It indicated that this kind of polymers had specific adsorption to patulin as compared with HMF–the adsorption rate in the SPE method and the adsorbance in the oscillation adsorption to PTL were 93.97% and 0.654μg/mg separately, while to HMF they were 76.89% and 0.496μg/mg respectively.Besides, the polymerization conditions were optimized with the results of SPE-HPLC research ,in terms of template institute, quantity of functional monomers and crosslinker, polymerization temperature and time.